Gear ratios and steppers Hi everyone,
I’m stuck, I’m trying to figure out the proper gear ratios for an indexing chuck using a nema 17 1.8 degree stepper
I’m mounting the big gear (125mm printed) on the back of main shaft on a mini lathe.
I’m okay designing and printing both gears but my issue is figuring out exact ratios to match the 200 steps.
My goal is to turn the lathe chuck 360 degrees in minimum 1 degree increments.
I need the big gear this big to provide mech advantage and mount stepper. The stepper will be able to swivel away from gear.
I hope I’ve provided enough info. Any help is appreciated.
Thanks
Rodhttps://reprap.org/forum/read.php?1,805456,805456#msg-805456
Sun, 15 Sep 2019 08:08:46 -0400Phorum 5.2.23https://reprap.org/forum/read.php?1,805456,805820#msg-805820Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805820#msg-805820
I have a 20 tooth aluminum gt2 pulley so I’m going with Etfrench’s system
It’s most likely a bit more forgiving than a printed gear.

I have to say this, I’ve watch this forum about 4 years.
I’ve been helped myself so many times in my hobby as have others.
Thank you to all those who spend their time to help others!
Cheers to all!!
Rod]]>TierodGeneralTue, 16 Jan 2018 10:05:16 -0500https://reprap.org/forum/read.php?1,805456,805603#msg-805603Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805603#msg-805603
p.s. The diameter of a module 1 gear is the same as the tooth count.]]>etfrenchGeneralSun, 14 Jan 2018 16:13:34 -0500https://reprap.org/forum/read.php?1,805456,805592#msg-805592Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805592#msg-805592
To get 1 degree per step on your lathe chuck the gear on the chuck needs to have 1.8 times as many teeth as the one on the stepper - e.g., 90 teeth on the chuck and 50 on the stepper. You will probably want to get a finer resolution but don't count fractional/microsteps beyond 1/2 or maybe 1/4 as the holding torque is not great. Without knowing what load you are putting on it I can't estimate but if it is something light I would use a 90 tooth 1 module ( about 90mm in diameter so fairly printable) gear to drive the chuck and a 20 tooth gear on the stepper: this combination will need 2.5 full steps or 5 half steps per degree. Consider using a steel HUCO spur gear such as the 101213020FAR instead of a 20 tooth printed gear - you may need to bore out the hub and drill for grub screws.

For the 90 tooth gear generate at module 1.0 and a 20 degree pressure angle. printed should be O.K. but depends on the cutting load.

Mike]]>leadinglightsGeneralSun, 14 Jan 2018 14:42:22 -0500https://reprap.org/forum/read.php?1,805456,805579#msg-805579Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805579#msg-805579
Dividers are built that way.
No need for a Nema23 and printed gears are close to worthless considering what is available and for cheap.]]>MKSAGeneralSun, 14 Jan 2018 13:01:23 -0500https://reprap.org/forum/read.php?1,805456,805563#msg-805563Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805563#msg-805563
so the higher the ratio the more accurate and better mech advantage.
what ill do is see how small a tooth i can accurately print and go with whatever ratio that is.
i should be able to print gears with at least 10:1 ratios with 125mm diam big gear.
I'm going to try the nema 17 as I'm only drilling small holes in plastic and aluminum.
I'm saving the link you gave me, thanks!

should i start a new topic some where else to ask about using mega/ramps and software?

thank you,
Rod]]>TierodGeneralSun, 14 Jan 2018 12:04:49 -0500https://reprap.org/forum/read.php?1,805456,805459#msg-805459Re: Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805459#msg-805459
I don't think NEMA 17 steppers are going to have enough torque to hold the work in place during the machining operation. The highest torque stepper I know of has 120 oz-in holding torque, more common are 60 oz-in motors. This NEMA 23 motor would be one I'd consider.]]>etfrenchGeneralSat, 13 Jan 2018 23:49:59 -0500https://reprap.org/forum/read.php?1,805456,805456#msg-805456Gear ratios and steppershttps://reprap.org/forum/read.php?1,805456,805456#msg-805456
I’m stuck, I’m trying to figure out the proper gear ratios for an indexing chuck using a nema 17 1.8 degree stepper
I’m mounting the big gear (125mm printed) on the back of main shaft on a mini lathe.
I’m okay designing and printing both gears but my issue is figuring out exact ratios to match the 200 steps.
My goal is to turn the lathe chuck 360 degrees in minimum 1 degree increments.
I need the big gear this big to provide mech advantage and mount stepper. The stepper will be able to swivel away from gear.
I hope I’ve provided enough info. Any help is appreciated.
Thanks
Rod]]>TierodGeneralSat, 13 Jan 2018 22:42:28 -0500